Project Summary/Abstract Power absorption and generation at the ankle is critical to gait efficiency, joint health, and safety. For amputees, it's also an important factor in residual limb health. Recently, research and commercial efforts have resulted in powered foot-ankle systems, which provide powered- plantarflexion electromechanically, reduce metabolic costs of walking, and show reductions in pathological loading of the contralateral limb. However, these devices are complex, expensive, heavy, and physically large ? all factors which limit widespread adoption. The objective of the energy-havesting mesofluidic impulse prosthesis (e-MIP) is to create an inexpensive, lightweight foot-ankle system which doesn't require a net energy input for powered plantarflexion and swing-phase dorsiflexion. The energy density and bandwidth of high pressure, meso-scale hydraulics enables an ankle that can seamlessly harvest the energy normally dissipated in gait; store it in fluid-accumulators; and reapply it in controlled, well timed power impulses. The benefits of powered systems are therefore realized in an anthropometric size and weight, with a system complexity that is clinically viable.